Electrosurgical instruments have been used for many years in high-frequency surgery, in particular to coagulate biological tissue, as well as to cut it. With coagulation, a high-frequency current is passed through the tissue being treated, causing it to alter due to protein coagulation and dehydration. The tissue contracts in such a way that the vessels occlude and bleeding is staunched. Once coagulation has occurred, the tissue can be cut through, for example, by means of a mechanically operating cutting instrument.
Electrosurgical procedures can be carried out in both a monopolar and a bipolar manner. With the monopolar technique the electrosurgical instrument has only a single current supply; accordingly, the tissue (or a patient) to be treated must be placed on the other potential. However, bipolar instruments which are configured with two sections electrically insulated from each other are increasingly gaining in importance. The current path between the electrode parts can thus be calculated and does not proceed any distance through the body of the patient. Thus the effect of, for example, pacemakers or other appliances which are connected to the patient during the operation is reduced.
Bipolar coagulating instruments have essentially two articulated limbs, at the proximal ends of which gripping devices are provided for handling the limbs. At the distal ends of the limbs, there are electrode parts for grasping tissue and for conducting the coagulating current through the tissue. Also, the HF current supplied by a HF generator is conducted via current-supplying devices to the electrode parts of the bipolar instrument.
Once coagulation has occurred, the cutting procedure is generally carried out by means of a cutting instrument. With mechanical cutting, the surgeon must exert force in order to carry out the cut, which, on the one hand, produces a mechanical strain on the cutting instrument and, on the other, promotes abrasive wear of the cutting sections. Also, as a result of such wear, particles of the cutting sections will remain in the tissue, causing an increased risk of infection.
A reduction in the expendable cutting force is effected with conventional cutting instruments, for example, by means of transmission mechanisms that are elaborate to manufacture and expensive. At the same time, the instruments are frequently constructed to be extremely stable, to counteract the mechanical strain. Instruments of a large constructed size, however, are precisely unsuited to endoscopic procedures.
Other solutions provide for the cutting sections to be coated, to reduce the abrasive wear. This requires an elaborate and expensive process. In addition, the coated sections can only be inadequately reworked, that is to say, for example, reground. To avoid reworking, the instruments, in particular the cutting sections, are often constructed as disposable or semi-reusable instruments, incurring high costs here, too.